Bump io.projectreactor:reactor-core from 3.4.39 to 3.4.40

Bumps [io.projectreactor:reactor-core](https://github.com/reactor/reactor-core) from 3.4.39 to 3.4.40.
- [Release notes](https://github.com/reactor/reactor-core/releases)
- [Commits](reactor/reactor-core@v3.4.39...v3.4.40)

---
updated-dependencies:
- dependency-name: io.projectreactor:reactor-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

buildSrc/build.gradle

@@ -64,7 +64,7 @@ dependencies {
 
     implementation 'io.github.gradle-nexus:publish-plugin:1.1.0'
     implementation 'io.spring.gradle:dependency-management-plugin:1.0.15.RELEASE'
-    implementation 'io.projectreactor:reactor-core:3.4.39'
+    implementation 'io.projectreactor:reactor-core:3.4.40'
     implementation 'com.apollographql.apollo:apollo-runtime:2.4.5'
     implementation 'com.github.ben-manes:gradle-versions-plugin:0.41.0'
     implementation 'com.github.spullara.mustache.java:compiler:0.9.14'